lkml.org 
[lkml]   [2023]   [Jun]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested()
    From
    On 2023/06/26 17:12, Sebastian Andrzej Siewior wrote:
    > On 2023-06-24 15:54:12 [+0900], Tetsuo Handa wrote:
    >> Why not to do the same on the end side?
    >>
    >> static inline void do_write_seqcount_end(seqcount_t *s)
    >> {
    >> - seqcount_release(&s->dep_map, _RET_IP_);
    >> do_raw_write_seqcount_end(s);
    >> + seqcount_release(&s->dep_map, _RET_IP_);
    >> }
    >
    > I don't have a compelling argument for doing it. It is probably better
    > to release the lock from lockdep's point of view and then really release
    > it (so it can't be acquired before it is released).

    We must do it because this is a source of possible printk() deadlock.
    Otherwise, I will nack on PATCH 2/2.

    >
    > Looking at other locking primitives (spin_lock_unlock(),
    > mutex_unlock(),…) that is what they do in the unlock path: lockdep
    > annotation followed by the actual operation. Therefore I would keep the
    > current ordering to remain in-sync with the other primitives.

    \
     
     \ /
      Last update: 2023-06-26 11:28    [W:7.767 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site